2001-04-08 04:00:00 PDT Johannesburg -- The last time snow fell on this city was Sept. 10, 1981. And you can just about count on one hand the number of days in the 20th century residents here saw any snow.

For the city's aspiring snowboarders, this would appear to be enough discouragement to keep them playing cricket, soccer or that other favorite pastime of South Africans, rugby.

But Johannesburg thrill-seekers are a determined bunch. After looking around and not finding anything to match the Alps or Rockies and no blizzards in the forecast, they lug their snowboards to the tops of the highest points in the city -- giant, yellowish heaps of gold-mine waste -- and let gravity take care of the rest.

"I thought, 'I can go down here,' " recalls Marco Caromba, a Johannesburg resident who in 1995 became the first person to take a snowboard down a pile of mine waste, according to the locals. And down he went -- reaching speeds as fast as 40 mph.

"I had plenty of people say I was crazy," he says.

Crazy or not, a new sport was born.

And so was his business, Pure Rush Industries, which is the only company in South Africa -- and most likely the world -- that offers "snowboarding" tours of some of the world's largest mine-waste heaps. Since starting six years ago, Caromba has taught hundreds of people -- many who have never seen snow -- how to make the best of Johannesburg's artificial mountains.

The sport is an offshoot of sandboarding, a popular distraction at beaches and deserts from California to Namibia (in southern Africa) to Dubai (on the Arabian Peninsula). But taking a snowboard down a sand dune is not quite the experience of barreling down mine waste, enthusiasts say.

The heaps of gold-mine waste, known locally as mine dumps, are made up of fine dust -- almost like baby powder to the touch. The dust particles were formed from crushed gold-bearing rock pulled from miles beneath Earth's surface. Since Johannesburg was founded more than 100 years ago, this material has built up to form hills more than 500 feet high.

Since 1887, when gold mining began in South Africa, more than 6 billion tons of ore have been taken from the ground, and production is about 100 million tons of ore a year.

To many Johannesburg residents, these strange dumps have become distinct landmarks of their city and a testament to its history as a gold boom town. From the air, they look like giant sandpiles, as if the entire region were under construction. A local newspaper columnist argued that the dumps are to Johannesburg what the pyramids are to Giza, the Eiffel Tower is to Paris or the Statue of Liberty is to New York.

But, for people who live near them, the dumps have a much darker past. Under apartheid, they served as man-made barriers between white neighborhoods and black townships. Black communities were placed downwind from the dumps, the fine dust blowing with the slightest breeze into their homes. Sprinkled with cyanide and other chemicals left over from the mining, the dust has posed serious health risks. Many township residents complain that the dust causes skin and eye irritations, respiratory ailments and silicosis of the lungs, a condition that hardens the lungs and makes breathing difficult.

Over the years, vegetation has been planted on the mine dumps to keep the blowing dust in place. Other residents have tried to put the dumps to use as canvases for giant outdoor artworks and, at one time, the site for a romantic drive-in restaurant. Now, hundreds of young South Africans have discovered that the scorned dumps happen to provide smooth, fast runs on snowboards.

Caromba plays down the health concerns of playing on the dumps.

"You would have to roll around in it for 24 hours with a wound to your artery or you would need to eat seven cups of the mine dust before it would do any harm," says Caromba, who during the week does marketing for a tobacco company. "Look at me. I've been doing this for six years, and I'm fine."

On a recent weekend, Caromba led a group of novice mine-dump boarders to a 400-foot pile of white and yellow waste in the Johannesburg suburb of Boksburg.

It is affectionately known as "Mount Mayhem."

The dump has a long way to go before it rivals Aspen or Snowbird as a tourist destination. To reach Mount Mayhem, visitors must travel down several miles of potholed mining roads, past the remnants of an abandoned gold mine, until a clearing opens up on one side of a huge dust hill topped with shrubs and grasses. No signs mark the way, and other than a dusty parking area, there are no amenities such as a snack bar, pub or souvenir shop.

Caromba reminds visitors that there's no lift, either. It's about a 20- minute hike to the expert runs and a shorter hike to the beginner's course. At the top, a strong wind is howling, picking up dust that clings to clothes and stings the eyes. From this height, it is possible to see dozens of nearby dumps that form a kind of mountain range.

Marlo Jooste, a 28-year-old from Pretoria, pushes off, gains speed and teeters like a tightrope walker before he falls and disappears in a cloud of dust. "It's a bit too much hard work for me. I'm feeling very unfit," says Jooste.

Jooste and other younger South Africans say they are drawn to the sport because it offers more adventure and excitement than soccer or cricket.

But don't expect du Plessis back on a mine dump soon. He'll return only if there is a lift system to the top. Such luxuries in this fledgling sport are unlikely, because soon the mine dumps of Johannesburg will be as rare as snow.

One by one, the dumps are disappearing as gold mining companies recycle them to extract remaining bits of gold hidden in the dust. Once the dumps are recycled, the land is then cleared for new development.